If one is equal to the reverse of another, keep only one of the pair. B.
> On Mar 29, 2018, at 9:48 PM, Ranjan Maitra <mai...@email.com> wrote: > > Dear friends, > > I would like to get all possible arrangements of n objects listed 1:n on a > circle. > > Now this is easy to do in R. Keep the last spot fixed at n and fill in the > rest using permuations(n-1, n-1) from the gtools package. > > However, what if clockwise or counterclockwise arrangements are the same? I > know that half of the above (n - 1)! arrangements are redundant. > > Is there an easy way to list these (n-1)!/2 arrangements? > > I thought of only listing the first half from a call to permuations(n - 1, n > - 1), but while this holds for n = 4, it does not for n = 5. So, I am > wondering if there is another function or tweak which would easily do this. > > Many thanks in advance for any help. and best wishes, > Ranjan > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
